RICEBLAST-NETWORKS — Result In Brief

Infection mechanisms in rice blast fungus

Blast disease is caused by the ascomycetous fungus Magnaporthe oryzae and is considered the most serious disease of rice around the world and also affects wheat, finger millet and maize. As M. oryzae can infect both leaf and root, it represents an excellent pathosystem for studying the organ specific mechanisms involved in fungal colonisation of rice leaves and roots.

The aim of the EU-funded project RICEBLAST-NETWORKS (Post-transcriptional networks regulating organ-specific and general infection mechanisms in the rice blast fungus) was to increase understanding of post-transcriptional networks that regulate organ-specific and general infection processes in the rice blast fungus.

Researchers studied the expression of early induced genes during plant growth to identify genes involved in the adjustment of the fungus to the plant environment. This enabled scientists to identify global changes in the fungal and plant transcriptome due to the recognition and response of different plant organs and the effect of time on gene expression.

Rice leaves and roots infected with a wild-type M. oryzae strain were used to conduct deep sequencing experiments that enabled scientists to follow changes in the fungus and the host plant. Tandem affinity purification experiments were also carried out using Exportin-5 protein (EXP5)-tagged with hemagglutinin protein tag (HA-FLAG) to identify proteins and RNAs that directly interact with EXP5.

To gain an insight into the mechanisms for polyadenylation and poly(A) site selection in M. oryzae, researchers used a new genome-wide sequencing approach to comprehensively map polyadenylation sites in M. oryzae. This allowed researchers to identify additional protein components and discover alternative polyadenylation signals in M. oryzae genes.

At present, there is a knowledge gap regarding Exp5-dependent cargoes in filamentous fungi and little is known about the post-transciptional mechanisms that regulate fungal plant infection. Therefore, the functional characterisation of EXP5, the RNA binding protein Rbp35 and genome-wide poly(A) mapping will increase knowledge on novel regulatory mechanisms regulating the presence of cis elements in messenger RNA (mRNA).

RICEBLAST-NETWORKS will help researchers understand the mechanisms behind M. oryzae, thereby aiding the development of effective and durable strategies to combat this devastating disease. It will also open up exciting avenues of research into local control of translation of proteins significant for M. oryzae plant invasion.